Wow! Long post! First of all, I would recommend trying to feed inside the enclosure with Kenyans. Pre-scent the room (make sure the prey items are thawing where the snake can smell it) warm up the pink very well with a hair dryer, then use tongs and hover it just above the substrate. If you can pass it in the snakes field of view, chances are good that it will strike. Another technique that works well. Is leaving the snake in a deli cup overnight with the prey.

On a side note, I would recommend using aspen bedding instead of sand. It holds their burrows much better, and sometimes a small husbandry change is all a snake needs to eat. Lastly, what are your cage temps?

Best of luck!
Benek